CN103248219B - Switching regulaor - Google Patents
Switching regulaor Download PDFInfo
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- CN103248219B CN103248219B CN201310049936.9A CN201310049936A CN103248219B CN 103248219 B CN103248219 B CN 103248219B CN 201310049936 A CN201310049936 A CN 201310049936A CN 103248219 B CN103248219 B CN 103248219B
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- 238000007599 discharging Methods 0.000 claims description 9
- 238000001514 detection method Methods 0.000 claims description 6
- 230000003334 potential Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 238000009499 grossing Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000006399 behavior Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002045 lasting Effects 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
Abstract
The present invention is provided with need not fine setting etc. and adjusts the switching regulaor of circuit that is operation, simple and that reliably detect short-circuit condition.The switching regulaor of the present invention is configured to: drive signal to control discharge circuit by the electrical power switching element of switching regulaor, when for short-circuit condition, electrical power switching element is always ON state, stop the action of discharge circuit, carry out the charging to electric capacity continuously, detect the charging voltage of electric capacity by voltage detecting circuit and reach the situation of more than a certain certain potentials, thus detect short-circuit condition.
Description
Technical field
The present invention relates to export the switching regulaor of constant voltage, more specifically, relate to the switching regulaor possessing short-circuit detecting circuit.
Background technology
Switching regulaor is used as the voltage supply source of the circuit of various electronic equipments.Certain voltage is exported to lead-out terminal by the function of switching regulaor with being not dependent on the variation in voltage of input terminal; but it is important for making short-circuit protection circuit action; the situation producing certain exception at lead-out terminal, supply increases over maximum current to the electric current loaded is detected (for example, referring to patent documentation 1) by this short-circuit protection circuit.
The circuit diagram of the existing switching regulaor possessing short-circuit detecting circuit is shown at Fig. 3.Existing switching regulaor is constituted by with lower component: the voltage of lead-out terminal Out carries out the output voltage bleeder circuit 20 of dividing potential drop, the reference voltage circuit 4 of output reference voltage Vref, relatively branch pressure voltage FB and the error amplifier 1 of reference voltage V ref, the triangular wave oscillating circuit 3 of output triangular signal Vramp, the output voltage of relative error amplifier 1 and triangular signal Vramp also export the PWM comparator circuit 2 of pulse-like signal, amplify the buffer circuits 5 of the output signal of PWM comparator 2, detect the short-circuit detecting circuit 100 that excessive electric current flows to the situation of lead-out terminal Out, electrical power switching element 200, inductance 201, diode 202 and smoothing capacity device 203.Short-circuit detecting circuit 100 is made up of the second reference voltage circuit 102 and comparator circuit 101.
Hereinafter, the action of existing switching regulaor is described.As it can be seen, existing switching regulaor uses PWM to control to carry out action.
The frequency of the triangular signal Vramp of triangular wave oscillating circuit 3 output is certain.Output signal Vpwm of PWM comparator 2 according to load current increase and decrease and dutycycle changes.Electrical power switching element 200 controls ON time by signal Vpwm.And, the output voltage Vout of lead-out terminal Out keeps certain value.
Fig. 4 is the sequential chart (timing chart) of existing switching regulaor.If condition as certain in load current period t1, then the dutycycle of signal Vpwm is certain.When as period t2, load current increases, the voltage Verr that error amplifier 1 is exported declines, and the dutycycle of signal Vpwm increases.Load current increases further, and voltage Verr less than the amplitude lower limit of triangular signal Vramp time, signal Vpwm persistently exports the fixed value making electrical power switching element 200 conducting state all the time.
Here, reference voltage V ref2 is set as the low voltage side of the amplitude lower limit relative to triangular signal Vramp.When reaching short-circuit condition as period t3, voltage Verr declines further.When voltage Verr is less than reference voltage V ref2, short-circuit detecting circuit 100 detects short-circuit condition, and the output voltage SD of comparator circuit 101 is reversed to L level.Buffer circuits 5 ends due to the voltage SD of L level, makes electrical power switching element 200 be not turned on.So, short-circuit detecting circuit 100 prevents switching regulaor constant flow overcurrent.
Patent documentation 1: Japanese Unexamined Patent Publication 5-328711 publication.
But, in the case of using the circuit output voltage Verr of above-mentioned error amplifier and reference voltage V ref2 compared, need to make reference voltage V ref2 outside the amplitude range of triangular signal Vramp, and close in the output voltage amplitude range of error amplifier.This has the disadvantage in that needs reference voltage V ref2 is finely adjusted adjustment behaviors such as (trimming), causes cost to increase.
Summary of the invention
The present invention designs to solve above such problem, uses easy circuit realiration to have the switching regulaor of the good short-circuit detecting circuit of accuracy of detection.
In order to solve existing problem, the switching regulaor with short-circuit detecting circuit of the present invention is following such structure.
Switching regulaor has short-circuit detecting circuit, and use the output signal of PWM comparator to control electrical power switching element, it is characterized in that, short-circuit detecting circuit possesses the voltage detecting circuit of the charging voltage of electric capacity, the charging circuit being charged electric capacity, the discharge circuit discharging electric capacity and supervision electric capacity, wherein, discharge circuit is controlled by the signal controlling electrical power switching element, during the lead-out terminal that electrical power switching element supplies energy to switching regulaor, discharge circuit stops discharging action.
Even if action not being counteracted owing to the precision of the detection level of voltage detecting circuit is extremely low, so the easy circuit such as phase inverter can be used to constitute voltage detecting circuit.
According to the switching regulaor possessing short-circuit detecting circuit of the present invention, have the following effects: the easy circuit that need not high-precision reference voltage can be used to constitute, it is possible to omit the adjustment unit of fine setting etc..
Accompanying drawing explanation
Fig. 1 is the circuit diagram of the switching regulaor possessing short-circuit detecting circuit of present embodiment；
Fig. 2 is the sequential chart of the switching regulaor of present embodiment；
Fig. 3 is the circuit diagram of the switching regulaor possessing existing short-circuit detecting circuit；
Fig. 4 is the sequential chart of existing switching regulaor.
Description of reference numerals
1 error amplifier；2 PWM comparators；3 triangular wave oscillating circuits；4 reference voltage circuits；5 buffer circuits；8 discharge circuits；9 charging circuits；11 voltage detecting circuits；20 bleeder circuits；100 short-circuit detecting circuits；101 comparator circuits；102 the 2nd reference voltage circuits；200 electrical power switching element.
Detailed description of the invention
Fig. 1 is the circuit diagram of the switching regulaor of present embodiment.
The switching regulaor of present embodiment possesses: output voltage bleeder circuit 20, reference voltage circuit 4, error amplifier 1, PWM comparator 2, triangular wave oscillating circuit 3, output buffer 5, electrical power switching element 200, inductance 201, diode 202, smoothing capacity device 203 and short-circuit detecting circuit 300.
The control terminal of electrical power switching element 200 is connected with the lead-out terminal of output buffer 5, is controlled by the output voltage of output buffer 5.Inductance 201 is connected between electrical power switching element 200 and lead-out terminal Out.Diode 202 is connected between one end and the ground terminal of inductance 201.Smoothing capacity device 203 is connected between the other end and the ground terminal of inductance 201.
Output voltage bleeder circuit 20 is connected with lead-out terminal Out, output voltage Vout carries out dividing potential drop and exports branch pressure voltage FB.The reference voltage V ref error originated from input amplifier 1 branch pressure voltage FB and reference voltage circuit 4 exported, is amplified their potential difference and exports as voltage Verr.Triangular wave oscillating circuit 3 is with certain rate-adaptive pacemaker triangular signal Vramp.Triangular signal Vramp and voltage Verr is inputted PWM comparator 2, and exports the signal Vpwm of pulse type.Output buffer 5 amplifies signal Vpwm, and exports the signal of drive power switch element 200.Short-circuit detecting circuit 300 detects the short-circuit condition of lead-out terminal Out by the signal Vpwm of PWM comparator 2, short-circuit condition detects signal SD and exports to output buffer 5.Output buffer 5 receives short-circuit condition detection signal SD, controls the driving of electrical power switching element 200.The voltage detecting circuit 11 of the voltage CD of the charging circuit 9 that electric capacity 10 by electric capacity 10, is charged by short-circuit detecting circuit 300, the discharge circuit 8 discharging electric capacity 10 and supervision electric capacity 10 is constituted.
Hereinafter, the action to the short-circuit detecting circuit of the switching regulaor of present embodiment, illustrate with figure.Fig. 2 is the sequential chart of the switching regulaor of present embodiment.
Discharge circuit 8 is controlled by the signal Vpwm of the electrical power switching element 200 controlling switching regulaor.Therefore, discharge circuit 8 supplies energy to during lead-out terminal Out stop discharging action in electrical power switching element 200, does not supply energy to during lead-out terminal Out carry out discharging action in electrical power switching element 200.Therefore, in fig. 2, the voltage CD of electric capacity 10 changes with the pulse width of signal Vpwm.
If the such load current of period t1 is certain condition, then the dutycycle of signal Vpwm is certain.When as period t2, load current increases, the voltage Verr that error amplifier 1 is exported declines, and the dutycycle of signal Vpwm increases.Correspondingly, the voltage CD of electric capacity 10 increases.
In period t3, when lead-out terminal Out short circuit, output voltage Vout declines, and electrical power switching element 200 always continues to supply energy to lead-out terminal Out.That is, signal Vpwm maintains L level.Therefore, discharge circuit 8 stops discharging action, charging circuit 9 charge electric capacity 10.The CD terminal voltage of electric capacity 10 rises, and when reaching the threshold voltage vt h of voltage detecting circuit 11, voltage detecting circuit 11 detects short-circuit condition, and short-circuit condition detects the output reversion of signal SD.
Here, the threshold level Vth of suitable setting voltage testing circuit in the way of can detecting the short circuit of lead-out terminal Out.That is, threshold level Vth is set as more than the voltage that electric capacity 10 is reached when the time of more than 2 cycles of signal Vpwm (such as 10 cycle) charges.It addition, the higher limit of the thermostability decision threshold voltage Vth by the element flowing super-high-current during short circuit.If it is said that in general, the time of stream super-high-current is about a few tens of milliseconds, then being unlikely to destroy.In the case of the 100kHz that operating frequency is slow, a cycle was 10 μ seconds.When the thermostability time of aforementioned components is assumed to 10m second, cycle conversion is equivalent to the amount in 1000 cycles.
Therefore, the setting value of threshold voltage vt h is set as Time Continuous more than 10 cycles of frequency of oscillation and below 1000 cycles the lasting charging voltage to the electric capacity 10 reached under electric capacity 10 charge condition by charging circuit 9.Even if this means that the setting accuracy of threshold voltage vt h is extremely low the most no problem, can simplifying the structure voltage detecting circuit 11.Therefore, even if constituting voltage detecting circuit 11 only with CMOS inverter, action does not have yet any improper.
As discussed above, owing to the switching regulaor of present embodiment is constituted short-circuit detecting circuit 300 by the circuit (such as phase inverter) of the short circuit by signal Vpwm detection lead-out terminal Out, it is possible to by need not fine setting etc. adjust operation, open-and-shut circuit structure detect short-circuit condition, prevent the overcurrent of switching regulaor.
And, the result that circuit is simplified is: owing to using minimum area to realize function, is also capable of cost and reduces this effect.
Claims (3)
1. a switching regulaor, has the short-circuit short-circuit detecting circuit that detection is connected to the load of lead-out terminal, and uses the output signal of PWM comparator to control electrical power switching element, it is characterised in that
Described short-circuit detecting circuit possesses electric capacity, the charging circuit being charged described electric capacity, the discharge circuit discharging described electric capacity and monitors the voltage detecting circuit of charging voltage of described electric capacity,
Described discharge circuit is controlled by the signal controlling described electrical power switching element, during the lead-out terminal that described electrical power switching element supplies energy to described switching regulaor, described discharge circuit stops discharging action, do not supply energy to the period of described lead-out terminal carry out discharging action in described electrical power switching element, so that the voltage of described electric capacity changes with the pulse width of the signal of the described electrical power switching element of control.
2. switching regulaor as claimed in claim 1, it is characterized in that, the detection voltage of described voltage detecting circuit is set as, more than the magnitude of voltage that in the case of the time at least 2 cycles of the action cycle continuing described switching regulaor of charging described electric capacity at described charging circuit, described electric capacity is reached.
3. switching regulaor as claimed in claim 1 or 2, it is characterised in that described voltage detecting circuit is made up of gate, is made the output of described electrical power switching element stop by the output of described voltage detecting circuit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012028735A JP6030836B2 (en) | 2012-02-13 | 2012-02-13 | Switching regulator |
| JP2012-028735 | 2012-02-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103248219A CN103248219A (en) | 2013-08-14 |
| CN103248219B true CN103248219B (en) | 2016-11-30 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1700597A (en) * | 2004-05-17 | 2005-11-23 | 精工电子有限公司 | Switch voltage stabilizer |
| CN1960148A (en) * | 2005-09-20 | 2007-05-09 | 精工电子有限公司 | Dc-dc converter including short-circuit protection circuit |
| CN100571001C (en) * | 2006-03-23 | 2009-12-16 | 株式会社理光 | Switching regulaor |
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1700597A (en) * | 2004-05-17 | 2005-11-23 | 精工电子有限公司 | Switch voltage stabilizer |
| CN1960148A (en) * | 2005-09-20 | 2007-05-09 | 精工电子有限公司 | Dc-dc converter including short-circuit protection circuit |
| CN100571001C (en) * | 2006-03-23 | 2009-12-16 | 株式会社理光 | Switching regulaor |
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| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20160310 Address after: Chiba County, Japan Applicant after: SEIKO INSTR INC Address before: Chiba, Chiba, Japan Applicant before: Seiko Instruments Inc. |
|
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder |
Address after: Chiba County, Japan Patentee after: EPPs Lingke Co. Ltd. Address before: Chiba County, Japan Patentee before: SEIKO INSTR INC |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20161130 Termination date: 20210208 |